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Is the iodine clock reaction a multistep one? Watch

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    If so can you explain? Oh and i'm asking about the one with peroxodisulphate, it's for my coursework.
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    Here are the equations:

    S2O8²‾(aq) + 2I‾(aq) → SO4²‾(aq) + I2(aq)
    2S2O3 ²‾(aq) + I2(aq) → S4O6²‾(aq) + 2I‾(aq)


    Thanks again
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    Yes

    First, Peroxydisulphate (VI) ions react with iodide ions to form iodine in the following oxidation reaction:
    S2O82- (aq) + 2I‾ (aq) → 2SO42-(aq) + I2(aq)

    However, some of the iodine is turned back into iodide ions by the sodium thiosulfate in a reduction reaction:
    I2(aq) + 2S2O32- (aq) → 2I‾ (aq) + S4O62-(aq)

    Once the sodium thiosulfate runs out, the excess I2 iodine remains in the solution. This iodine can be detected by its dark colour, a change which can be enhanced by adding several drops of starch solution to react with it. The concentrations of each of the reactants and the temperature can be varied, which will affect the time it takes to produce a certain amount of iodine, and so for the solution to change colour.
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    (Original post by grassgrazers01)
    Yes

    First, Peroxydisulphate (VI) ions react with iodide ions to form iodine in the following oxidation reaction:
    S2O82- (aq) + 2I‾ (aq) → 2SO42-(aq) + I2(aq)

    However, some of the iodine is turned back into iodide ions by the sodium thiosulfate in a reduction reaction:
    I2(aq) + 2S2O32- (aq) → 2I‾ (aq) + S4O62-(aq)

    Once the sodium thiosulfate runs out, the excess I2 iodine remains in the solution. This iodine can be detected by its dark colour, a change which can be enhanced by adding several drops of starch solution to react with it. The concentrations of each of the reactants and the temperature can be varied, which will affect the time it takes to produce a certain amount of iodine, and so for the solution to change colour.
    Thanks a lot this was really helpful
 
 
 
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